Benzene derivative having long, linear conjugated structure, process for producing benzene derivative, and liquid-crystal material

ABSTRACT

The present invention provides, in a method for transporting charge using the molecular orientation in a liquid-crystalline state, a novel benzene derivative having a long, linear conjugated structure expected to have satisfactory charge-transport properties without photoexcitation, a process for producing the benzene derivative, and a liquid-crystal material including the benzene derivative. The benzene derivative having a long, linear conjugated structure is represented by general formula (1):

TECHNICAL FIELD

The present invention relates to a novel benzene derivative having along, linear conjugated structure, the benzene derivative being usefulas a charge-transport material used in, for example, optical sensors,organic electroluminescent elements (EL elements), photoconductors,spatial modulators, thin-film transistors, charge-transport substancesfor electrophotographic photoreceptors, photolithographic materials,solar cells, nonlinear optical materials, organic semiconductorcapacitors, or other sensors. The present invention also relates to aliquid-crystal material and a process for producing the benzenederivative.

BACKGROUND ART

In recent years, organic electroluminescent elements using organicmaterials as hole-transport materials or charge-transport materialsconstituting the electroluminescent elements have been intensivelystudied.

As such charge-transport materials, for example, anthracene derivatives,anthraquinoline derivatives, imidazole derivatives, styryl derivatives,hydrazone derivatives, triphenylamine compounds,poly(N-vinylcarbazoles), and oxadiazoles are known.

Liquid-crystal compounds have been used as materials for displays andapplied to various devices, such as clocks, desktop electroniccalculators, television sets, personal computers, and cellular phones.The liquid-crystal materials are classified into thermotropic liquidcrystals (liquid crystals in which transitions depend on temperature)and lyotropic liquid crystals (liquid crystals in which transitionsdepend on concentration) on the basis of the mechanisms of phasetransitions. From the standpoint of molecular arrangements, these liquidcrystals are classified into three groups: smectic liquid crystals,nematic liquid crystals, and cholesteric liquid crystals. The liquidcrystals are also known as anisotropic liquids and exhibit opticalanisotropy similarly to optically uniaxial crystals. Observation usingan orthoscope is usually performed between crossed Nicols, and is usefulfor the identification of types of liquid crystals and for thedetermination of the transition temperatures of liquid-crystal phases.The smectic liquid crystals are classified into A, B, C, D, E, F, and Gon the basis of characteristic birefringent optical patterns observedwith the orthoscope.

Hanna et al. have found that liquid-crystal compounds having smecticphases are capable of transporting charges and have proposedcharge-transport materials using the liquid crystal compounds. They haveproposed, for example, a liquid-crystalline charge-transport materialexhibiting smectic liquid crystallinity and having a reduction potentialof −0.3 to −0.6 (V vs. SEC) with reference to a standard calomelelectrode (SEC) (Japanese Unexamined Patent Application Publication No.09-316442); a liquid-crystalline charge-transport material including aliquid crystalline compound exhibiting a smectic phase havingself-orientation properties and a predetermined amount of fullerene C70having a sensitizing effect (Japanese Unexamined Patent ApplicationPublication No. 11-162648); a polymer membrane in which aliquid-crystalline charge-transport material is dispersed in the polymermatrix, in other words, a polymer membrane in which a liquid-crystallinecompound exhibiting a smectic phase is dispersed (Japanese UnexaminedPatent Application Publication No. 11-172118); a liquid-crystallinecharge-transport material including a mixture containing a smecticliquid-crystalline compound (Japanese Unexamined Patent ApplicationPublication No. 11-199871); a liquid-crystalline charge-transportmaterial having smectic liquid crystallinity and having an electronmobility or hole mobility of 1×10⁻⁵ cm²/v·s or more (Japanese UnexaminedPatent Application Publication No. 10-312711); and a liquid-crystallinecharge-transport material including a smectic liquid crystallinecompound having, in one molecule, a functional group capable of forminga new intermolecular or intramolecular bond and a functional groupcapable of transporting a hole and/or electron (Japanese UnexaminedPatent Application Publication No. 11-209761).

Smectic liquid-crystalline compounds disclosed in the above-describedPatent Documents include smectic liquid-crystalline compounds eachhaving a 6-π-electron aromatic ring such as a benzene ring, a pyridinering, a pyrimidine ring, a pyridazine ring, a pyrazine ring, or atropolone ring; smectic liquid-crystalline compounds each having a10-π-electron aromatic ring such as a naphthalene ring, azulene ring, abenzofuran ring, an indole ring, an indazole ring, a benzothiazole ring,a benzoxazole ring, a benzimidazole ring, a quinoline ring, anisoquinoline ring, a quinazoline ring, or a quinoxaline ring; andsmectic liquid-crystalline compounds each having a 14-π-electronaromatic ring such as a phenanthrene ring, or an anthracene ring. Inthese compounds, charges are transported in a smectic-A phase. However,the above-described method for transporting charges requiresphotoexcitation. Furthermore, conductivity is 10⁻¹³ s/cm withoutphotoexcitation and 10⁻¹¹ s/cm in a photoexcited state. The conductivityvalues are the same levels as those of an insulating material.

DISCLOSURE OF THE INVENTION

The present inventors have proposed a method for transporting charge byapplying a voltage to a liquid-crystalline compound in a smectic-B phaseor in a solid state due to phase transition from the smectic-B phase(Japanese Unexamined Patent Application Publication No. 2001-351786).

The present invention has been accomplished in view of such knowntechniques. It is an object of the present invention to provide, in amethod for transporting charge using the molecular orientation in aliquid-crystalline state, a novel benzene derivative having a long,linear conjugated structure expected to have satisfactorycharge-transport properties without photoexcitation, a process forproducing the benzene derivative, and a liquid-crystal materialincluding the benzene derivative.

A first aspect of the present invention provides a benzene derivativehaving a long, linear conjugated structure represented by generalformula (1):

wherein R¹ represents a straight or branched alkyl group, an alkoxygroup, or a group having an unsaturated bond represented by generalformula (2):

(wherein R³ represents a hydrogen atom or a methyl group, and Brepresents an alkylene group, —CO—O—(CH₂)n, —C₆H₄—CH₂—, or —CO—), R²represents an alkyl group or an alkoxy group, and X represents a halogenatom.

A second aspect of the present invention provides a process forproducing a benzene derivative having a long, linear conjugatedstructure represented by general formula (1):

(wherein R¹, R², and X are the same as described above), the processincluding a first step of allowing a benzaldehyde derivative representedby general formula (3):

to react with a phosphonium salt represented by (4):

(wherein R⁴, R⁵, and R⁶ are each a monovalent organic group, and Arepresents a halogen atom), in the presence of a base to produce apyridine derivative represented by general formula (5):

(wherein R¹ is the same as described above); and a second step ofallowing the pyridine derivative to react with a halogenated compoundrepresented by general formula (6):R²—X  (6)(wherein R² and X are the same as described above).

A third aspect of the present invention provides a liquid-crystalmaterial including a benzene derivative having a long, linear conjugatedstructure represented by general formula (1) described above or acompound derived from the benzene derivative.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail below.

A novel compound provided by the present invention is a benzenederivative having a long, linear conjugated structure represented bygeneral formula (1).

R¹ in the benzene derivative having a long, linear conjugated structurerepresented by general formula (1) represents a straight or branchedalkyl group, an alkoxy group, or a group having an unsaturated bondrepresented by general formula (2). The alkyl group has 1 to 18 carbonatoms. Specific examples thereof include a methyl group, an ethyl group,a butyl group, a pentyl group, a hexyl group, an octyl group, a dodecylgroup, pentadecyl group, and an octadecyl group. Among these, an alkylgroup having 6 to 18 carbon atoms is particularly preferable.Furthermore, when the alkyl group is a branched alkyl group representedby general formula: CH₃—(CH₂)_(m)—CH(CH₃)—(CH₂)_(n)—CH₂— (wherein nrepresents 0 to 7, and m represents 0 to 7), the solubility of thebenzene derivative can be improved.

The alkoxy group is represented by general formula: C_(n)H_(2n+1)O,wherein n is preferably 1 to 18 and particularly preferably 6 to 18.

R³ in the group having an unsaturated bond represented by the generalformula (2) represents a hydrogen atom or a methyl group. B representsan alkylene group, —CO—O—(CH₂)n-, —C₆H₄—CH₂—, or —CO—. The alkylenegroup may be straight or branched and preferably has 1 to 18 carbonatoms. Specific examples thereof include a methylene group, an ethylenegroup, a trimethylene group, a tetramethylene group, a pentamethylenegroup, an ethylethylene group, a propylene group, a butylene group, ahexylene group, an octadecylene group, a nonylene group, a decylenegroup, and a dodecylene group. Furthermore, n in —CO—O—(CH₂)_(n)— isparticularly preferably 1 to 18.

R² in the benzene derivative having a long, linear conjugated structurerepresented by general formula (1) represents an alkyl group or analkoxy group. The alkyl group has 1 to 18 carbon atoms. Specificexamples thereof include a methyl group, an ethyl group, a butyl group,a pentyl group, a hexyl group, an octyl group, a dodecyl group, apentadecyl group, and an octadecyl group. Among these, an alkyl grouphaving 1 to 8 carbon atoms is particularly preferred. The alkoxy groupis represented by general formula: C_(n)H_(2n+1)O, wherein n ispreferably 1 to 20 and particularly preferably 1 to 8.

X in the benzene derivative having a long, linear conjugated structurerepresented by general formula (1) represents a halogen atom such asbromine, chlorine, or iodine.

In the present invention, the benzene derivative having a long, linearconjugated structure represented by general formula (1) is a novelcompound. With respect to a conformation, the benzene derivative may bea cis-isomer, a trans-isomer, or a mixture of cis- and trans-isomers.

A process for producing the benzene derivative having a long, linearconjugated structure represented by general formula (1) will bedescribed below.

The process for producing the benzene derivative having a long, linearconjugated structure according to the present invention basicallyincludes a first step and a second step described below.

<First Step>

The first step is a step of producing a pyridine derivative representedby general formula (5), the pyridine derivative being prepared by thereaction shown in reaction formula (1):

(wherein R¹, R⁴, R⁵, R⁶, and A are the same as described above).

The benzaldehyde derivative, which is a first material used in the firststep, represented by general formula (3) can be prepared by performingsteps A-1 to A-4 according to reaction scheme (2):

(wherein R¹ is the same as above, Rs each represent a monovalent organicgroup, and X¹ and X² each represent a halogen atom).

Step A-1 is a step of producing a compound represented by generalformula (9) by reaction of a halide (compound (7)) with a hydroxybenzylalcohol (compound (8)) in a solvent in the presence of a base.

R¹ in the halide (compound (7)) is a group corresponding to R¹ in thebenzaldehyde derivative, which is a reaction material used in the firststep, represented by general formula (3) and also corresponds to R¹ inthe benzene derivative having a long, linear conjugated structurerepresented by general formula (1). X¹ represents a halogen atom such asbromine, chlorine, or iodine.

In step A-1, 1 to 3 and preferably 1 to 1.5 moles of the halide(compound (7)) and 1 to 3 and preferably 1 to 1.5 moles of the base,such as sodium hydroxide, potassium hydroxide, sodium ethoxide, orsodium methoxide are used per mole of the hydroxybenzyl alcohol(compound (8)). The reaction is performed in an alcohol solvent, such asmethanol or ethanol, at 0° C. to 100° C. and preferably 60° C. to 80° C.for 1 to 20 hours and preferably 5 to 10 hours.

In step A-2, a compound (compound (9)) prepared in step A-1 is allowedto react with a phosphorus halide (compound (10)) in a solvent toprepare a compound represented by general formula (11).

X² in the phosphorus halide (compound (10)) represents a halogen atomsuch as bromine, chlorine, or iodine.

In step A-2, 1 to 3 and preferably 1 to 1.5 moles of the phosphorushalide (compound (10)) is used per mole of the compound (compound (9))prepared in step A-1. The reaction is performed in a solvent, such asethyl ether, at −30° C. to 60° C. and preferably 0° C. to 30° C. for 1to 10 hours and preferably 1 to 5 hours.

In step A-3, the compound (compound (11)) prepared in step A-2 isallowed to react with a phosphine compound (compound (12)) in a solventto prepare a compound represented by general formula (13).

R represents in the phosphine compound (compound (12)) represents amonovalent organic group. The type of R is not limited as long as thecompound represented by general formula (11) can be converted into aphosphonium salt. To be specific, for example, a trialkylphosphine, suchas triphenylphosphine, trimethylphosphine, or triethylphosphine, may beused.

In step A-3, 1 to 3 and preferably 1 to 1.5 moles of the phosphinecompound (compound (12)) is used per mole of the compound (compound(11)) prepared in step A-2. The reaction is performed in a solvent, suchas methylene chloride, chloroform, or dichloroethane, at 20° C. to 100°C. and preferably 50° C. to 70° C. for 1 to 10 hours and preferably 3 to5 hours.

In step A-4, a compound (13) prepared in step A-3 is allowed to reactwith terephthalaldehyde (compound (14)) in the presence of a base toprepare a benzaldehyde derivative, which is a reaction material used inthe first step, represented by general formula (3).

In step A-4, 1 to 3 and preferably 1 to 1.5 moles of terephthalaldehyde(compound (14)) and 1 to 5 and preferably 1 to 3 moles of the base, suchas sodium hydroxide, potassium hydroxide, sodium ethoxide, or sodiummethoxide, are used per mole of the compound (compound (13)) prepared inA-3. The reaction is performed in an alcohol solvent, e.g., methanol orethanol −30° C. to 30° C. and preferably −5° C. to 15° C. for 3 to 15hours and preferably 5 to 10 hours.

In a production process of the present invention, if necessary, afterstep A-4, the trans-isomer of the benzaldehyde derivative (compound (3))can be selectively produced by heating the resulting benzaldehydederivative (compound (3)) in a solvent in the presence of iodine.Subsequently, reaction in the first step can be performed while thetrans conformation is maintained. Therefore, the trans-isomer of thebenzene derivative represented by general formula (1) can be selectivelyproduced in high yield.

In this case, 0.001 to 0.1 and preferably 0.005 to 0.01 moles of iodineis added per mole of benzaldehyde derivative (compound (3)). The heatingtemperature is 100° C. to 180° C. and preferably 130° C. to 150° C.Examples of a solvent that can be used include benzene, toluene,o-xylene, m-xylene, p-xylene, chlorobenzene, o-dichlorobenzene,m-dichlorobenzene, and p-dichlorobenzene. These solvent may be usedalone or in combination of two or more.

The other reaction material used in the first step, i.e., thephosphonium salt represented by general formula (4) can be prepared, forexample, according to reaction formula (3):

(wherein R⁴, R⁵, and R⁶ are the same as described above, X³ represents ahalogen atom).

X³ in the halogenated pyridine compound (compound (15)) represents ahalogen atom such as bromine, chlorine, or iodine. R⁴, R⁵, and R⁶ in thephosphine compound (compound (16)) each represent a monovalent organicgroup. The types of R⁴, R⁵, or R⁶ are not limited as long as thepyridine derivative represented by general formula (15) can be convertedinto a phosphonium salt. For example, a phenyl group or an alkyl grouphaving 1 to 5 carbon atoms. R⁴, R⁵, and R⁶ may be the same or different.Specific examples of the phosphine compound include triphenylphosphine,trimethylphosphine, and triethylphosphine.

To be specific, 1 to 3 and preferably 1 to 1.5 moles of the phosphinecompound (16) and 1 to 3 and preferably 1 to 1.5 moles of sodium iodide(compound (17)) are used per mole of the halogenated pyridine compound(compound (15)). The reaction is performed in a solvent, such asmethylene chloride, chloroform, or dichloroethane, at 0° C. to 100° C.and preferably 40° C. to 70° C. for 1 to 10 hours and preferably 1 to 5hours.

In the first step of the present invention, the benzaldehyde derivativerepresented by general formula (3) is allowed to react with thephosphonium salt represented by general formula (4) in a solvent in thepresence of a base.

Here, 1 to 5 and preferably 1 to 3 moles of the phosphonium saltrepresented by general formula (4) is added per mole of the benzaldehydederivative represented by general formula (3).

Examples of the base that can be used in the first step include, but arenot limited to, metal hydrides such as sodium hydride; amines such astrimethylamine and triethylamine; alkali hydroxides such as potassiumhydroxide and sodium hydroxide; alkoxides such as sodium methoxide,potassium methoxide, sodium ethoxide, and potassium ethoxide; and othercompounds such as piperidine, pyridine, potassium cresolate, andalkyllithium. These compounds may be used alone or in combination of twoor more.

Here, 1 to 5 and preferably 1 to 3 moles of the base is added per moleof the benzaldehyde derivative represented by general formula (3).

Examples of the reaction solvent include ethers such as dioxane,tetrahydrofuran, and dibutyl ether; nitrites such as acetonitrile andpropionitrile; alcohols such as methanol and ethanol; and othercompounds such as dimethylformamide, acetone, and water. These may beused alone or in combination of two or more.

With respect to reaction conditions, the reaction temperature is −20° C.to 50° C. and preferably 0° C. to 30° C. The reaction time is 1 to 15hours and preferably 3 to 10 hours.

After the reaction, if necessary, purification, such as washing orrecrystallization, is performed to produce a pyridine derivativerepresented by general formula (5).

In the production process according to the present invention, before thesecond step, the trans-isomer of the pyridine derivative (compound (5))can be selectively produced by heating the resulting pyridine derivative(compound (5)) in a solvent in the presence of iodine. Subsequently,reaction in the second step can be performed while the transconformation is maintained. Therefore, the trans-isomer of the benzenederivative represented by general formula (1) can be selectivelyproduced in high yield.

In this case, 0.001 to 0.1 and preferably 0.005 to 0.01 moles of iodineis added per mole of the pyridine derivative (compound (5)). The heatingtemperature is 100° C. to 180° C. and preferably 130° C. to 150° C.Examples of a solvent that can be used include benzene, toluene,o-xylene, m-xylene, p-xylene, chlorobenzene, o-dichlorobenzene,m-dichlorobenzene, and p-dichlorobenzene. These solvents may be usedalone or in combination of two or more.

(Second Step)

The second step is a step of producing the benzene derivative having along, linear conjugated structure represented by general formula (1),the benzene derivative being prepared by the reaction shown in reactionformula (4):

(wherein R¹, R², and X are the same as described above).

R² and X in the halogenated compound (compound (6)), which is a reactionmaterial used in the second step, correspond to R² and X, respectively,in the benzene derivative having a long, linear conjugated structurerepresented by general formula (1). R² represents an alkyl group or analkoxy group. The alkyl group has 1 to 18 carbon atoms. Specificexamples thereof include a methyl group, an ethyl group, a butyl group,a pentyl group, a hexyl group, an octyl group, a dodecyl group, apentadecyl group, and an octadecyl group. Among these, an alkyl grouphaving 1 to 8 carbon atoms is particularly preferred. The alkoxy groupis represented by general formula: C_(n)H_(2n+1)O, wherein n ispreferably 1 to 20 and particularly preferably 1 to 8. X represents ahalogen atom such as bromine, chlorine, or iodine.

In the second step, the pyridine derivative represented by generalformula (5) is allowed to react with the halogenated compoundrepresented by general formula (6) in a solvent.

Here, 10 to 300 or more and preferably 100 to 200 moles of thehalogenated compound represented by general formula (6) is added permole of the pyridine derivative represented by general formula (5).

Examples of the reaction solvent include methylene chloride, chloroform,and dichloromethane. These may be used alone or in combination of two ormore.

With respect to reaction conditions, the reaction temperature is 0° C.to 100° C. and preferably 30° C. to 60° C. The reaction time is 10 to 50hours and preferably 20 to 40 hours.

After the reaction, if necessary, purification, such as washing orrecrystallization, is performed to produce a benzene derivative having along, linear conjugated structure represented by general formula (1).

The resulting benzene derivative having a long, linear conjugatedstructure represented by general formula (1) is a novelliquid-crystalline compound.

Next, the liquid-crystal material according to the present inventionwill be described.

The liquid-crystal material according to the present invention includesthe benzene derivative having a long, linear conjugated structurerepresented by general formula (1) or a compound derived from thebenzene derivative having a long, linear conjugated structure.

The term “compound derived from the benzene derivative having a long,linear conjugated structure represented by general formula (1)”(hereinafter, referred to as “polymer”) means a homopolymer or copolymerof the benzene derivative; a polymeric compound cross-linked with thebenzene derivative using a cross-linking agent; or a polymeric compoundprepared by addition reaction of the benzene derivative with ahydrosilyl group-containing polymeric compound, wherein R¹ in thebenzene derivative having a long, linear conjugated structure representsa group, which is represented by general formula (2), having anunsaturated bond.

Here, the polymer includes at least a repeating unit represented bygeneral formula (18) or (19):

(wherein R², R³, B, and X are the same as described above).

The polymer may include a repeating unit, which is a copolymercomponent, derived from, for example, acrylic acid, methacrylic acid, orstyrene. When the polymer is a copolymer, the content of the repeatingunit represented by general formula (18) or (19) is 50 mole percent ormore, preferably 70 mole percent or more, and most preferably 80 molepercent or more.

The number-average molecular weight of the polymer is in the range of1,000 to tens of millions and preferably tens of thousands to millions.

The polymer can be produced by the following method. For example, inorder to produce a homopolymer or copolymer of the benzene derivativerepresented by general formula (1) or a polymeric compound cross-linkedwith the benzene derivative using a cross-linking agent, either apredetermined monomer alone or a mixture of a predetermined monomer witha cross-linking agent may be polymerized in the presence of apolymerization initiator by radical polymerization such as solutionpolymerization, suspension polymerization, emulsion polymerization, orbulk polymerization.

Furthermore, in order to produce a polymeric compound by additionreaction of a hydrosilyl group-containing polymeric compound with thebenzene derivative having a long, linear conjugated structurerepresented by general formula (1), the hydrosilyl group-containingpolymeric compound is allowed to react with the benzene derivativehaving a long, linear conjugated structure represented by generalformula (1) in the presence of platonic chloride, a platonic chloridealcohol solution, a complex of platinum and an olefin complex, or arhodium catalyst such as a rhodium carbonyl complex.

The liquid-crystal material according to the present invention is amaterial exhibiting smectic liquid crystallinity and including thebenzene derivative having a long, linear conjugated structurerepresented by general formula (1), a composition containing the benzenederivative having a long, linear conjugated structure, theabove-described polymer, or a composition containing the polymer.

In the composition containing the benzene derivative having a long,linear conjugated structure represented by general formula (1), thecontent of the benzene derivative having a long, linear conjugatedstructure represented by general formula (1) is at least 30 percent byweight or more, preferably 50 percent by weight or more, and mostpreferably 90 percent by weight or more. Furthermore, the compositionexhibits smectic liquid crystallinity due to the liquid-crystallinecompound having a long, linear conjugated structure represented bygeneral formula (1).

The other components in the composition are used for adjusting the phasetransition temperature of the benzene derivative having a long, linearconjugated structure represented by general formula (1). For example,other liquid-crystalline compounds or other compounds each having along, linear conjugated structure and having an alkyl group or analkoxide group at its ends may be used alone or in combination of two ormore. The other compounds each having a long, linear conjugatedstructure and having an alkyl group or an alkoxide group at its ends maybe a liquid-crystalline compound or not. These other components may beused alone or in combination of two or more.

The composition containing the benzene derivative having a long, linearconjugated structure represented by general formula (1) can be preparedas follows: the benzene derivative having a long, linear conjugatedstructure represented by general formula (1) and a predeterminedcomponent described above are dissolved in a solvent, and then thesolvent is removed by heating, under a reduced pressure, or the like;the benzene derivative having a long, linear conjugated structurerepresented by general formula (1) and a predetermined componentdescribed above are mixed and melted by heating; or sputtering, vacuumevaporation, or the like.

In the composition containing the polymer, the content of the polymer isat least 30 percent by weight or more, preferably 50 percent by weightor more, and most preferably 80 percent by weight or more. Furthermore,the composition exhibits smectic liquid crystallinity due to theliquid-crystalline compound, i.e., the benzene derivative, having along, linear conjugated structure represented by general formula (1).

The other components in the composition are used for adjusting the phasetransition temperature of the polymer. For example, otherliquid-crystalline compounds or other compounds each having a long,linear conjugated structure and having an alkyl group or an alkoxidegroup at its ends may be used alone or in combination of two or more.The other compounds each having a long, linear conjugated structure andhaving an alkyl group or an alkoxide group at its ends may be aliquid-crystalline compound or not. These other components may be usedalone or in combination of two or more.

The composition containing the polymer can be prepared as follows: thepolymer and a predetermined component described above are dissolved in asolvent, and then the solvent is removed by heating, under a reducedpressure, or the like; the polymer and a predetermined componentdescribed above are mixed and melted by heating; or sputtering, vacuumevaporation, or the like.

The liquid-crystal material according to the present invention can beused as a charge-transport material capable of transporting charge byapplying a voltage to the liquid-crystal material in aliquid-crystalline state or in a solid state due to phase transition ofthe liquid-crystalline state, and can be used for a charge-transportmaterial used in, for example, optical sensors, organicelectroluminescent elements (EL elements), photoconductors, spatialmodulators, thin-film transistors, charge-transport substances forelectrophotographic photoreceptors, photolithographic materials, solarcells, nonlinear optical materials, organic semiconductor capacitors, orother sensors.

EXAMPLES

While the present invention will be described in detail based onexamples below, it is understood that the invention is not limitedthereto.

Synthetic Example

1. Preparation of Benzaldehyde Derivative Used as Reaction Material Usedin First Step

Synthetic Example 1-1 Synthesis of 10-bromo-1-decene (Compound (22))

According to reaction formula (5), 10-bromo-1-decene was synthesized.

First, 24.67 g (0.15 M) of 9-decene-1ol (compound (20)) was dissolved in180 mL of diethyl ether. The system was purged with nitrogen and cooledin ice. At a solution temperature of 5° C. or less, 2,256 g (0.075 M) ofphosphorus tribromide (compound (21)) was added dropwise thereto. Afterdropwise addition, stirring was performed at 15° C. for 17 hours. Theresulting solution was cooled in ice. At a solution temperature of 5° C.or less, 95 mL of methanol was added dropwise. After the dropwiseaddition, 190 g of a sodium hydrogen carbonate aqueous solution (1 M)was added dropwise, and then stirring was stopped. Next, phaseseparation was performed. The separated organic layer was washed with105 g of brine. The resulting organic layer was concentrated anddistilled (85° C., 1.8 mmHg) to produce 18.83 g of a target10-bromo-1-decene (compound (22)) (yield: 57.2%).

<Identification data>

¹H-NMR (δ, CDCl₃): 1.2-1.5 (m, 10H, —(CH₂)₅—), 1.8-1.9 (m, 2H, —CH₂—),2.0-2.1 (m, 2H, —CH₂—), 3.4 (t, 2H, —CH₂Br), 4.9-5.0 (m, 2H, CH₂═),5.7-5.9 (m, 1H, ═CH—).

Synthetic Example 1-2 Synthesis of 9-decenoxybenzyl alcohol (Compound(23))

According to reaction formula (6), 9-decenoxybenzyl alcohol (compound(23)) was synthesized.

First, 12.80 g (0.10 M) of 4-hydroxybenzyl alcohol (compound (8)) wasdissolved in ethanol 190 mL, and 4.0 g (0.10 M) of sodium hydroxide wasadded thereto. The resulting mixture was heated to 65° C. After heating,24.14 g (0.11 M) of 10-bromo-1-decene (compound (22)) prepared inSynthetic example 1-1 was added dropwise, and the resulting mixture wasaged at a mixture temperature of 76° C. for 6 hours. Next, the generatedsalt was removed by decantation, and the reaction solution wasconcentrated. After concentration, the resulting solution was dilutedwith 350 mL of diethyl ether and washed twice with 100 mL of deionizedwater. After washing, the organic layer was concentrated to producecrude crystals. The crude crystals were recrystallized twice from 25 mLof hexane. The recrystallized crystals were washed with hexane anddried. Thereby, 16.88 g of 9-decenoxybenzyl alcohol (compound (23)) wasproduced (yield: 64.3%).

<Identification Data>

¹H-NMR (δ, CDCl₃): 1.3-1.6 (m, 10H, —(CH₂)₅—), 1.7-1.8 (m, 2H, —CH₂—),2.0-2.1 (m, 2H, —CH₂—), 3.9 (t, 2H, —CH₂O—), 4.6 (d, 2H, —CH₂OH),4.9-5.0 (m, 2H, CH₂═), 5.7-5.9 (m, 1H, ═CH—), 6.8-6.9 (m, 2H, —OPh-),7.2-7.3 (m, 2H, -PhCH₂—). FAB-MASS (Xe): 263 (MH+).

Synthetic Example 1-3 Synthesis of 9-decenoxybenzyl bromide (Compound(24))

According to reaction formula (7), 9-decenoxybenzyl bromide (compound(24)) was synthesized.

First, 16.05 g (0.061 M) of 9-decenoxybenzyl alcohol (compound (23))prepared in Synthetic example 1-2 was dissolved in 85 mL of diethylether, and the solution was cooled to 0° C. After cooling, 6.76 g (0.022M) of phosphorus tribromide (compound (21)) was added dropwise theretoat 5° C. or less. The mixture was aged at 5° C. for 2 hours and then at15° C. for 1.5 hours. After aging, the solution was cooled to 5° C.Then, 38 mL of methanol was added dropwise at 5° C. or less. Afterdropwise addition, 73.4 g of a sodium hydrogen carbonate aqueoussolution (1 M) was added dropwise at 10° C. or less, and then phaseseparation was performed. After the separation, the separated organiclayer was washed with 32 mL of deionized water and then concentrated.Thereby, 18.19 g of 9-decenoxybenzyl bromide (compound (24)) wasproduced (yield: 91.6%).

<Identification Data>

¹H-NMR (δ, CDCl₃): 1.3-1.5 (m, 10H, —(CH₂)₅—), 1.7-1.8 (m, 2H, —CH₂—),2.0-2.1 (m, 2H, —CH₂—), 3.9 (t, 2H, —CH₂O—), 4.5 (s, 2H, —CH₂Br),4.9-5.0 (m, 2H, CH₂═), 5.7-5.9 (m, 1H, ═CH—), 6.8-6.9 (m, 2H, —OPh-),7.2-7.3 (m, 2H, -PhCH₂—), FAB-MASS (Xe): 325 (M+).

Synthetic Example 1-4 Synthesis of 9-decenoxybenzyltriphenylphosphoniumbromide (Compound (26))

According to reaction formula (8), 9-decenoxybenzyltriphenylphosphoniumbromide (compound (26)) was synthesized.

First, 17.23 g (0.053 M) of 9-decenoxybenzyl bromide (compound (24))prepared in Synthetic example 1-3 and 13.92 g (0.053M) oftriphenylphosphine (compound (25)) were added to 53 mL of chloroform.The resulting mixture was heated to 60° C. and then aged for 1.5 hours.After aging, the resulting reaction mixture was concentrated to producecrude crystals. The resulting crude crystals were washed with diethylether, filtrated, and dried. Thereby, 29.19 g of9-decenoxybenzyltriphenylphosphonium bromide (compound (26)) wasproduced (yield: 93.7%).

<Identification Data>

¹H-NMR (δ, CDCl₃): 1.3-1.5 (m, 10H, —(CH₂)₅—), 1.7-1.8 (m, 2H, —CH₂—),2.0-2.1 (m, 2H, —CH₂—), 3.8 (t, 2H, —CH₂O—), 4.9-5.0 (m, 2H, —CH₂═), 5.2(d, 2H, —CH₂P—), 5.7-5.9 (m, 1H, ═CH—), 5.2 (d, 2H, —CH₂P—), 6.6 (d, 2H,—OPh-), 7.0 (dd, 2H, -PhCH₂—), 7.6-7.8 (m, 15H, (Ph)₃). ³¹P-NMR (δ,CDCl₃): 28.0 ppm. FAB-MASS (Xe): 507 (M−Br).

Synthetic Example 1-5 Synthesis of 9-decenoxystilbene aldehyde (Compound(27))

According to reaction formula (9), 9-decenoxystilbene aldehyde (compound(27)) was synthesized.

First, 23.07 g (0.039 M) of 9-decenoxybenzyltriphenylphosphonium bromide(compound (26)) prepared in Synthetic example 1-4 and 5.91 g ofterephthalaldehyde (compound (14)) were dissolved in 315 mL of ethanol.The resulting solution was cooled to −2° C., and then 25.64 g of asodium ethoxide ethanol solution (21 percent by weight, aldrich) wasadded dropwise at 0° C. or less. Aging was performed at a mixturetemperature of 0° C. or less for 1.5 hours and then at a mixturetemperature of 10° C. to 15° C. for 2 hours. After aging, 39 g ofdeionized water was added dropwise. Then, the precipitated crystals werefiltrated and washed with 50 mL of 60% aqueous ethanol and 30 mL ofethanol, followed by drying. Thereby, 7.12 g of 9-decenoxystilbenealdehyde (compound (27)) was produced (yield: 50.0%).

<Identification Data>

¹H-NMR (δ, CDCl₃): 1.3-1.5 (m, 10H, —(CH₂)₅—), 1.7-1.8 (m, 2H, —CH₂—),2.0-2.1 (m, 2H, —CH₂—), 3.9-4.0 (m, 2H, —CH₂O—), 4.9-5.0 (m, 2H, —CH₂═),5.7-5.9 (m, 1H, ═CH—), 6.5-7.9 (m, 10H, Ph, —CH═CH—). FAB-MASS (Xe): 363(MH+).

Subsequently, 14 mL of p-xylene and 8.2 mg iodine were added to 4.34 g(0.012 M) of 9-decenoxystilbene aldehyde (compound (27)). The resultingmixture was heated to 140° C. and aged for 4 hours. After aging, themixture was cooled to room temperature. The precipitated crystals werefiltrated and washed with 25 mL of ethanol, followed by drying. Then, 88mL of chloroform was added to the resulting crystals, followed bystirring at room temperature for 20 minutes. After stirring, insolublematter was removed by filtration, and then the filtrate was concentrate.Thereby, the trans-isomer of 2.35 g of 9-decenoxystilbene aldehyde(compound (27)) was produced (yield: 54.1%).

<Identification Data>

¹H-NMR (δ, CDCl₃): 1.3-1.5 (m, 10H, —(CH₂)₅—), 1.7-1.8 (m, 2H, —CH₂—),2.0-2.1 (m, 2H, —CH₂—), 3.9 (t, 2H, —CH₂O—), 4.9-5.0 (m, 2H, CH₂═),5.7-5.9 (m, 1H, ═CH—), 6.9 (d, 2H, —OPh-), 7.0 (d, 1H, —CH═CH—), 7.2 (d,1H, —CH═CH—), 7.5 (d, 2H, Ph), 7.6 (d, 2H, Ph), 7.8 (d, 2H, Ph).FAB-MASS (Xe): 363 (MH+).

2. Preparation of Phosphonium Salt Used as Reaction Material Used inFirst Step

Synthetic Example 2-1 Synthesis of 4-chloromethylpyridine (Compound(30))

According to reaction formula (10), 4-chloromethylpyridine (compound(30)) was synthesized.

First, 10.19 g (0.06 M) of 4-chloromethylpyridine hydrochloride(compound (28)) was dissolved in 29.91 g of deionized water, and 20.60 gof 12% sodium hydroxide (compound (29)) aqueous solution was addeddropwise thereto. After dropwise addition, 60.15 g of dichloromethanewas added, and phase separation was performed. The separated organiclayer was concentrated to produce 7.52 g of 4-chloromethylpyridine(compound (30)) (yield: 98.0%).

<Identification Data>

¹H-NMR (δ, CDCl₃): 4.5 (s, 2H, CH₂Cl), 7.31-7.34 (m, 2H, Py), 8.61-8.67(m, 2H, Py).

Synthetic Example 2-2 Synthesis of Pyridinium MethyltriphenylphosphoniumIodide (Compound (31))

According to reaction formula (11), pyridiniummethyltriphenylphosphonium iodide (compound (31)) was synthesized.

First, 7.97 g (0.06 M) of 4-chloromethylpyridine (compound (30))prepared in Synthetic example 2-1 and 15.77 g (0.06 M) oftriphenylphosphine (compound (25)) were dissolved in 97.81 g ofchloroform. Then, 48.57 g of a solution prepared by dissolving 9.11 g(0.06 M) of sodium iodide in deionized water was added thereto. Theresulting mixture was heated to 70° C. and aged for 2 hours. Afteraging, the reaction mixture was subjected to phase separation. After theseparated organic layer was concentrated, the precipitated crystals werefiltrated and washed with 36.11 g of chloroform, followed by drying.Thereby, 15.80 g of pyridinium methyltriphenylphosphonium iodide(compound (31)) was produced (yield: 54.5%).

<Identification Data>

¹H-NMR (δ, DMSO₃): 5.25 (d, 2H, CH₂P), 6.95-6.98 (m, 2H, Py), 7.68-7.80(m, 12H, Ph), 7.87-7.96 (m, 3H, Ph), 8.41-8.43 (m, 2H; Py). FAB-MASS(Xe): 355 (M−1).

Example 1

<First Step>

Synthesis of Trans-isomer of Pyridine Derivative (Compound (33))

According to reaction formula (12), a pyridine derivative (compound(33)) was synthesized.

First, 3.18 g (0.0044 M) of pyridinium methyltriphenylphosphonium iodide(compound (31)) prepared in Synthetic example 2-2 was dissolved in 22.40g of methanol, and 4.29 g of a sodium ethoxide (compound (32)) ethanolsolution (21 percent by weight, aldrich) was added dropwise thereto.Then, 22.53 g of chloroform containing 1.59 g of 9-decenoxystilbenealdehyde (compound (27)) prepared in Synthetic example 1-5 was addeddropwise at room temperature. After dropwise addition, the reactionmixture was aged at room temperature for 3 hours and then concentrated.After concentration, the resulting crude crystals were washed with 19.61g of methanol and then filtrated, followed by drying. Thereby, 1.64 g ofcrude crystals of a pyridine derivative (compound (33)) was produced(yield: 85.1%).

<Identification Data>

FAB-MASS (Xe): 438 (MH+).

Subsequently, 1.64 g (0.00374 M) of the resulting crude crystals of thepyridine derivative (compound (33)) and 2.5 mg of iodine were added to11.5 g of p-xylene. The resulting mixture was heated with a bath havinga temperature of 150° C. and aged for 4 hours. Then, the mixture wascooled to room temperature, and the precipitated crystals were washedwith ethanol. Thereby, 0.73 g of the trans-isomer of the pyridinederivative (compound (33)) was produced (yield: 45.1%).

<Identification Data>

¹H-NMR (δ, CDCl₃): 1.20-1.50 (m, 10H, —(CH₂)₅—), 1.76-1.82 (m, 2H,—CH₂—), 2.00-2.20 (m, 2H, —CH₂—), 3.98 (t, 2H, —CH₂O—), 4.92-5.01 (m,2H, CH₂═), 5.75-5.88 (m, 1H, ═CH—), 6.82-6.93 (d, 2H, Ph), 6.95 (d, 1H,—CH═), 7.02 (d, 1H, —CH═), 7.11 (d, 1H, —CH═), 7.30 (d, 1H, —CH═),7.35-7.38 (m, 2H, Py), 7.42-7.57 (m, 6H, Ph), 8.55-8.60 (m, 2H, Py).FAB-MASS (Xe): 438 (MH+).

<Second Step>

Synthesis of Trans-isomer of Benzene Derivative (Compound (35))

According to reaction formula (13), a benzene derivative (compound (35))was synthesized.

First, 1.18 g (0.0027 M) of the trans-isomer of the pyridine derivative(compound (33)) prepared in the first step and 60.77 g of ethyl bromide(compound (34)) were added to 59.11 g of chloroform, and the resultingmixture was stirred under heating at 40° C. for 40 hours. After aging,the reaction mixture was concentrated to produce crude crystals. Then,27.33 g of acetone was added to the resulting crude crystals. Theresulting mixture was heated to 60° C. and filtrated under heating.Thereby, 1.04 g of the target benzene derivative (compound (35)) wasproduced (yield: 70.7%).

<Identification Data>

¹H-NMR (δ, CDCl₃): 1.26-1.50 (m, 10H, —(CH₂)₅—), 1.70 (t, 3H, —CH₃),1.76-1.82 (m, 2H, —CH₂—), 2.00-2.20 (m, 2H, —CH₂—), 3.97 (t, 2H,—CH₂O—), 4.88 (ddd, 2H, —CH₂—), 4.90-5.03 (m, 2H, —CH₂═), 5.75-5.88 (m,1H, ═CH—), 6.90 (d, 2H, —OPh-), 6.95 (d, 1H, —CH═), 7.11 (d, 1H, —CH═),7.16 (d, 1H, —CH═), 7.45 (d, 2H, —OPh-), 7.52 (d, 2H, -Ph-), 7.60 (d,2H, -Ph-), 7.67 (d, 1H, —CH═), 8.01 (d, 2H, Py), 9.17 (d, 2H, Py).FAB-MASS (Xe): 467 (M−Br).

IR (KBr, cm−1): 3,022 (aromatic C—H stretching vibration), 2,924-2,853(aliphatic C—H stretching vibration), 1,642 (C═C stretching vibration),1,590-1,467 (C═C, C═N skeletal vibration), 1,253 (C—O—C antisymmetricstretching vibration), 966 (—C═C— out-of-plane deformation vibration),839 (aromatic C—H in-plane deformation vibration).

In addition, the gap between two glass substrates was filled with theresulting benzene derivative (compound (35)) and heated to a temperatureexceeding the liquid crystal-isotropic liquid transition temperature.Light transmitted through the benzene derivative was observed with apolarizing microscope. The observation indicated that the benzenederivative was a liquid-crystalline compound exhibiting a smectic phaseoriented perpendicularly to the substrates.

INDUSTRIAL APPLICABILITY

As has been described above, an inventive benzene derivative having along, linear conjugated structure represented by general formula (1) isa novel compound. The benzene derivative having a long, linearconjugated structure is a compound having smectic liquid crystallinity.A liquid-crystal material containing the benzene derivative having along, linear conjugated structure or a compound derived from thederivative can be used as a charge-transport material capable oftransporting charge by applying a voltage to the liquid-crystal materialin a liquid-crystalline state or in a solid state due to phasetransition of the liquid-crystalline state, and can be used for acharge-transport material used in, for example, optical sensors, organicelectroluminescent elements (EL elements), photoconductors, spatialmodulators, thin-film transistors, charge-transport substances forelectrophotographic photoreceptors, photolithographic materials, solarcells, nonlinear optical materials, organic semiconductor capacitors, orother sensors.

1. A liquid crystal benzene derivative having a long, linear conjugatedstructure represented by general formula (1):

wherein R¹ represents a straight or branched alkyl group having 6 to 18carbon atoms, an alkoxy group having 6 to 18 carbon atoms, or a grouphaving an unsaturated bond represented by general formula (2):

(wherein R³ represents a hydrogen atom or a methyl group, and Brepresents an alkylene group, —CO—O—(CH₂)n, —C₆H₄—CH₂—, or —CO—), R²represents an alkyl group or an alkoxy group, and X represents a halogenatom.
 2. A process for producing a benzene derivative having a long,linear conjugated structure represented by general formula (1):

wherein R¹ represents a straight or branched alkyl group having 6 to 18carbon atoms, an alkoxy group having 6 to 18 carbon atoms, or a grouphaving an unsaturated bond represented by general formula (2):

(wherein R³ represents a hydrogen atom or a methyl group, and Brepresents an alkylene group, —CO—O—(CH₂)n, —C₆H₄—CH₂—, or —CO—), R²represents an alkyl group or an alkoxy group, and X represents a halogenatom, the process comprising: a first step of allowing a benzaldehydederivative represented by general formula (3):

(wherein R¹ the same as defined in general formula (1) above); to reactwith a phosphonium salt represented by (4):

(wherein R⁴, R⁵ and R⁶ are each a monovalent organic group, and Arepresents a halogen atom), in the presence of a base to produce apyridine derivative represented by general formula (5):

(wherein R¹ is the same as described in general formula (1) above); anda second, step of allowing the pyridine derivative to react with ahalogenated compound represented by general formula (6):R²—X  (6) (wherein R² and X are the same as described in general formula(1) above).
 3. A liquid-crystal material comprising: a liquid crystalbenzene derivative having a long, linear conjugated structurerepresented by general formula (1):

wherein R¹ represents a straight or branched alkyl group having 6 to 18carbon atoms, an alkoxy group having 6 to 18 carbon atoms, or a grouphaving an unsaturated bond represented by general formula (2):

(wherein R³ represents a hydrogen atom or a methyl group, and Brepresents an alkylene group, —CO—O—(CH₂)n, —C₆H₄—CH₂—, or —CO—), R²represents an alkyl group or an alkoxy group, and X represents a halogenatom.